The present invention relates to a line jammer device for, in a locked state, jamming a line which is under tension upstream of the device and, in an unlocked state, releasing this line.
The term xe2x80x9cupstreamxe2x80x9d defines that end of the line which is connected to the object that has to be tensioned using this line, and the term xe2x80x9cdownstreamxe2x80x9d defines the opposite end.
This device is intended in particular to be used on pleasure sailing boats, to jam various lines involved in the rigging of these boats, particularly the halyards, but this application is not restrictive. The term xe2x80x9cupstreamxe2x80x9d then, in the case of a halyard, defines that end of the line that is connected to the sail, and the term xe2x80x9cdownstreamxe2x80x9d defines the end via which the halyard is intended to be manipulated using a capstan.
Such line jammer devices are known in principle and are in widespread use on sailing boats.
An existing device, generally known by the name of a jamming cleat, comprises two pivoting cams, returned so that they pivot toward one another, and each having a curved lateral portion on its side that faces the other cam. The line is engaged between these cams, against the return force exerted on them, and the tension it experiences upstream causes the cams to pivot in the direction that causes the line to be gripped by these cams.
A device of this type exhibits a number of drawbacks, particularly as regards its limited ability to withstand high tension, the difficulty in releasing the line when such tension is exerted, the need to reinsert the line between the cams after each release, and the not insignificant amount of wear that the grip of the cams causes to the line.
These drawbacks appreciably restrict the use of these devices.
Another type of device, generally known by the name of a cam cleat, comprises a mount through which the line passes, and a cam with an eccentric which can move in terms of pivoting in this mount. The cam can be moved between a locked position in which it grips the line between it and the bottom of the mount, and an unlocked position in which it is located some distance from the line and therefore does not impede the free running of this line through the device.
This type of device is stronger than the jamming cleats described hereinabove, but retains many of their drawbacks. In particular, the cam may become very difficult, if not impossible, to manipulate if high tension is exerted on the line, as this entails exerting tension on this line downstream of the device to balance the tension upstream and thus allow the line to be released. Exerting this downstream tension entails an additional manipulation, preventing quick release of this line in certain emergency situations. Furthermore, the wear generated on the line by this type of device is high and the grip produced is not very effective on certain high-strength fibers, the coefficient of friction of which is low.
A third type of existing device comprises a mount containing a series of platelets, these platelets being inclinable and pierced with holes. The line is engaged through these holes and the tension it experiences causes the platelets to incline. This inclination allows the platelets to press firmly against the line, which jams the latter.
This type of device slightly reduces the amount of line wear but does not overcome the aforementioned drawbacks.
There is also known, from documents DE 1 231 and FR 2 753 169, a line jammer device comprising a first line-gripping member and a second line-gripping member between which this line is engaged. Said first gripping member is mounted so that it can pivot with respect to the device and comprises a circular surface around which the line can be engaged, and said second gripping member is arranged with respect to said first gripping member in such a way as to allow said line to be gripped between it and said first gripping member. At least one of these members can move between a locked position in which it grips the line between it and the other member, and an unlocked position in which it does not exert said gripping effort, so as to allow the line to run through the device.
These devices retain the aforementioned drawbacks relating to the difficulty of releasing the line in the event of high tension, to the not insignificant wear generated on the line and to the lack of gripping efficiency with certain lines.
The present invention sets out specifically to overcome these fundamental drawbacks of devices of this type by providing a line jammer device which allows both easy and quick release of the line in all circumstances, without the need to exert tension on the line downstream of the device, perfect jamming of a line made of fibers with a low coefficient of friction, and low line wear.
The device to which the invention relates comprises a first line-gripping member and a second line-gripping member like those disclosed in the aforementioned documents DE 1 231 and FR 2 753 169.
According to the invention,
the device is shaped in such a way that the line can be wound around said first gripping member over a fraction of a turn corresponding to an angle of more than 180xc2x0, or over a number of turns, and
said second gripping member is arranged with respect to said first gripping member in such a way that the grip it exerts on the line is exerted once the line has been wrapped around said first gripping member by a fraction of a turn corresponding to an angle of at least 180xc2x0, or once the line has been wound around said first gripping member over a number of turns.
Winding the line around said first gripping member makes it possible to greatly reduce the residual tension experienced by the line at the second gripping member. The grip exerted by the latter can therefore be reduced accordingly, thus limiting the wear generated on the line and the forces experienced by said members in this gripping. What this means is that manipulating the mobile gripping member or members with a view to releasing the line is easy, thus eliminating the need to tension the line downstream of the device to facilitate or achieve this release. Furthermore, winding the line in the aforementioned way gives a broad contact area between this line and said first gripping member, thus generating significant amounts of friction which increase with the tension exerted on the line. This friction combines with the gripping of the line to allow the latter to be jammed perfectly even when it is made of fibers which have a low coefficient of friction.
According to one simple embodiment of the invention, the mobile gripping member or members may be movable only by manually operated manipulating means, for example using a lever. According to a preferred embodiment of this invention, the device at the same time comprises:
manually operated manipulating means for bringing the mobile gripping member or members into their unlocked position, these manipulating means allowing the line to be released so that it can run; and
means allowing the mobile gripping member or members to be moved automatically into said locked position when the tension upstream is greater than the tension downstream and allowing these same members to be moved automatically into said unlocked position when the downstream tension is at least equal to the upstream tension.
A device such as this prevents any risk of uncontrolled release of the line while it is being manipulated.
According to one possibility, in this case of automatic movement, the second gripping member can move and consists of a pivoting cam, it being possible for this pivoting cam to pivot in one direction to engage with the line, when the tension upstream is greater than the tension downstream, and to pivot in the opposite direction to release the line when the tension exerted downstream is at least equal to the tension exerted upstream.
According to another possibility in this same instance, said first gripping member can be moved toward the second gripping member when the tension upstream is greater than the tension downstream, and can be moved in the direction away from this second gripping member when the tension exerted downstream is at least equal to the tension exerted upstream.
The first gripping member may be a transverse cylinder or may consist of a drum mounted so that it can rotate on a spindle. In this second instance, the line is made to run more easily through the device by the rotation of the drum, this allowing a quick action for releasing the line.
As a preference, in this case, the device comprises releasable means for preventing the drum from rotating in the direction that corresponds to the exerting of a tension upstream that is greater than the tension downstream; these means may in particular consist of a ratchet system connected to the device and of corresponding teeth formed on the drum.
Advantageously, in this case, the device comprises manually operated manipulating means designed to allow the following:
when the device is in a locked position, the line to be jammed if the tension upstream is greater than the tension downstream,
when the device is in an intermediate unlocked position, said second gripping member to be moved into its unlocked position while at the same time keeping said releasable means for preventing the drum from rotating in an active position, in which they prevent this rotation, and
when the device is in a fully unlocked position, the second gripping member to be kept in its unlocked position and said releasable means for preventing the drum from rotating to be moved into an inactive position, in which they allow this rotation.
In said intermediate unlocked position, the line can slip around the drum without the drum rotating, and therefore with friction, this corresponding to controlled release of the line. In said fully unlocked position, the drum is free to rotate so that this drum is made to turn by the running of the line, which corresponds to quick release of this line.
According to an improved embodiment of the invention, the second gripping member comprises, some way away from its gripping zone intended to come into contact with the line, a first cylindrical part, parallel to the axis of the drum, forming said ratchet and, on the same side as this gripping zone, a second cylindrical part, also parallel to said axis; this second cylindrical part is engaged, with the possibility of pivoting and of sliding, in a slot; this slot is oriented in such a way that the movement of said second cylindrical part within it causes the second gripping member to pivot about the axis of said first cylindrical part into its locked position when this second gripping member is moved in a curve by the drum via said first cylindrical part engaging with one of the teeth of the drum following the exerting on the upstream part of the line of a tension that is greater than the tension downstream.
The ratchet is thus formed directly on the second gripping member, and said slot allows this second gripping member to move slightly in a curve when the tension upstream greater than the tension downstream causes the drum to rotate. This curved movement, because of the orientation of the slot, allows the second gripping member to be moved toward this drum, until the line is gripped.
According to a further improved implementation of this embodiment of the invention:
the device comprises a mount on which a lever is mounted so that it can pivot, this lever being able to move between a locked position, an intermediate unlocked position and a fully unlocked position corresponding to the aforementioned locked, intermediate unlocked, and fully unlocked positions of the device;
said slot is formed in this lever and allows said second gripping member to move when the lever is placed in said locked position, whereas it is distant from the drum when the lever is pivoted into said intermediate unlocked position;
the mount of the device comprises a cam surface against which said second cylindrical part bears as the lever is pivoted into the intermediate unlocked position; this cam surface has a curved shape and said second cylindrical part collaborates with it in such a way as to cause the second gripping member to pivot about the first cylindrical part while keeping this first cylindrical part in engagement with the corresponding tooth of the drum; and
the lever comprises a stud which bears against the second gripping member when this lever is moved into said fully unlocked position, so as to disengage said first cylindrical part from the corresponding tooth of the drum.
When the lever is in the locked position, the slot allows the second gripping member to move automatically as indicated hereinabove. The pivoting of the lever into said intermediate unlocked position allows this same slot to be moved away from the drum and therefore allows the second gripping member to be moved into its unlocked position; however, this movement occurs without the ratchet that said first cylindrical part forms disengaging from the corresponding tooth of the drum, because of the collaboration between said second cylindrical part and said cam surface. Pivoting the lever into the fully unlocked position disengages the ratchet from the tooth of the drum.
Advantageously, the first gripping member comprises ribs which project, radially outward, from its exterior peripheral face, these ribs making it possible to increase the friction between the line and this first gripping member.
The possibilities of the line slipping with respect to this first gripping member are thus reduced, which encourages control over the release of said line.
Advantageously, the second gripping member is formed of the assembly of two parts, one of which comprises said first and second cylindrical parts, and the other of which comprises said line gripping zone, means being provided for allowing one of these parts to be placed relative to the other in a number of longitudinal positions and for keeping these parts in a predetermined position.
The movement of one of these parts with respect to the other allows the position of said gripping zone to be adjusted along this second gripping member, and therefore allows this position to be adapted to suit the diameter of the line that is to be jammed, to obtain optimum gripping of this line.
As a preference, the hub of the drum comprises an axial cavity which has a non-circular profile and opens to the outside of the device, this cavity being able to accommodate means for allowing this drum to be rotated by hand so that the line can be fully or partially tensioned. These means may, in particular, comprise a ratchet system, such as a needle ratchet system and a winding handle, particularly a capstan handle.